Apparatus for continuously casting and cooling while advancing through a body of liquid coolant

ABSTRACT

An apparatus for continuously casting metal in which a molten metal is cast continuously by introducing molten metal under pressure through a mold to form a partially solidified casting with a solid shell. The casting so formed is advanced substantially horizontally directly into contact with a bath of liquid coolant and at a depth at which the pressure acting on the periphery of the solid casting shell sufficiently counteracts the pressure of the molten core in this casting to prevent rupture. The casting is maintained substantially at this depth until the casting is sufficiently solidified in the coolant to prevent outbreak of the molten core, and the casting so sufficiently solidified is discharged continuously from the coolant bath.

United States Patent 2,363,695 11/1944 Ruppik Howard A. Fromson Rouges Ridge Road, Weston, Conn. 06880 829,921

June 3, 1969 Division of Ser. No. 596,292, Nov. 22, 1966, Pat. No. 3, 468,361

Patented Mar. 16, 1971 lnventor Appl. No. Filed APPARATUS FOR CONTINUOUSLY CASTING AND COOLING WHILE ADVANCING THROUGH A BODY OF LIQUID COOLANT 3 Claims, 1 Drawing Fig.

US. Cl 164/283 Int. Cl 822d 11/12 Field of Search 164/81, 82, 89,128, 281-283 References Cited UNITED STATES PATENTS 3,128,513 4/1964 Charlton et a1. 164/89 3,151,366 10/1964 Fromson l64/283x 3,324,932 6/1967 Ayers 164/89 3,430,680 3/1969 Leghorn 164/81 Primary Examiner-Charles W. Lanham Assistant Examiner-R. Spencer Annear AttorneyBurgess, Ryan and Hicks ABSTRACT: An apparatus for continuously casting metal in which a molten metal is cast continuously by introducing molten metal under pressure through a mold to form a partially solidified casting with a solid shell. The casting so formed is advanced substantially horizontally directly into contact with a bath of liquid coolant and at a depth at which the pressure acting on the periphery of the solid casting shell sufficiently I counteracts the pressure of the molten core in this casting to prevent rupture. The casting is maintained substantially at this depth until the casting is sufficiently solidified in the coolant to prevent outbreak of the molten core, and the casting so sufficiently solidified is discharged continuously from the coolant bath.

APPARATUS FOR CONTINUOUSLY CASTING AND COOLING WHILE ADVANCING THROUGH A BODY OF LIQUID COOLANT This invention relates to the art of continuous casting of molten metal. This application is a division of my copending application Ser. No. 596,292 filed Nov. 22, 1966 and maturing into U.S. Pat. No. 3,468,361.

in the continuous casting of a molten metal, such as steel, such metal is led into one end of a water-cooled mold, which may be made of copper or a copper alloy. The mold is open at both ends and may be of any convenient cross-sectional shape, but is usually round or rectangular in cross section. The metal in contact with the mold walls solidifies, forming a solid shell which remains filled with a molten metal core. This shell is continually pulled from the exit end of the mold, and as further cooling progresses, the molten core gradually solidifies.

In order that economic advantage may be derived from the use of continuous casting, the rate of flow of metal through the mold must be increased as far as possible. This requirement means that a withdrawal rate which allows the formation of a thick shell within the mold istoo slow. Those portions of the shell which are either still within the mold or adjacent the exit thereof are apt to be weak. This weakness is the result of the high temperature of the solidified metal and the relative thinness of the shell. As a result of this weakness the shell may rupture and the liquid metal in the core break forth. It is an object of the invention to provide anew and improved apparatus for lessening the strain on the thin shell of solidified metal and thus avoid such breakthroughs.

It is a further object of the invention to provide a new and improved apparatus for increasing the casting rate by lessening the strain upon the thin shell.

lt is a still further object of the invention to provide an apparatus establishing the emerging casting, such as an ingot, in a horizontal position, thereby reducing the height of the space required to contain the casting equipment.

In the drawing a ladle is shown. The ladle supplies molten metal to a refractory tundish 11 through ladle pipe 12. An exit pipe 13 provides a path by which the molten metal 14 in the tundish may reach a mold 15: Water passages 16 allow cooling of mold 15, which may be made of copper. The mold has interior surfaces defining a mold bore 17. The walls of the mold bore 17 may be parallel or, as shown in the drawing, they may have a straight-sided portion and an exit portion where the walls flare outward so that the cross-sectional area of the bore increases from the entrance to the exit.

in the mold bore 17 the molten metal contacts the interior walls, freezes, and forms a solid shell 18 surrounding a molten core 19. As the casting, as for example, in the form of the ingot 25, leaves the mold bore 17, it proceeds horizontally through a bath of molten salt 20, which may be barium chloride. The salt is contained in a chamber comprised of refractory walls 21 and a refractory floor 22. Cooling passages 23 are embedded in the chamber walls to facilitate the removal of heat from the salt and'a rotatable stirrer 24 may be provided to direct a current of salt against the ingot 25 as it emerges from the mold.

The static pressure of the head of molten salt above the ingot tends to counteract the static head of molten metal within the ingot core. This external pressure thus balances the internal pressure and lessens the tendency of the latter to rupture the solid shell 18. Since the ingot is horizontal the desired pressure balance can be maintained along its whole length even though the metal being cast may be considerably denser than the salt.

As the ingot progresses through the bath of molten salt it is supported by rollers 26 which may be rotatably held in loose metal journals. The salt will tend to lubricate such bearings. In addition, the apparent weight of the ingot on the rollers is reduced by the flotation effect of the salt bath.

An opening for the ingot to leave the salt bath is provided by a copper exit ring 27 having internal passages 28 through which a coolin solution may be passed. A central openin defined by su ace 29 15 provided hrough the exit ring, sai

opening being aligned with the opening in mold bore 17. The central opening is shaped to conform to the surface of the ingot as it passes therethrough, but preferably a small space is left between the surface 29 and the surface of the ingot in order to prevent wear of the exit ring. Molten salt enters this space and freezes due to contact with the exit ring 27. This salt acts as packing to prevent undueloss of salt from the mass within the chamber. The film of salt left upon the emerging ingot may be cracked therefrom by rolls or other devices, or washed off by cooling water. A tray 30 is provided to receive such salt fragments, which may be periodically returned to the salt chamber.

Further cooling of the ingot may be accomplished by water spray nozzles 31, after which the ingot may be cut into pieces of a desired length by any suitable means.

Although the invention is shown producing a single continuous casting, the apparatus can be employed to produce at the same time, two or more continuous castings through the same molten salt bath.

lclaim:

1. An apparatus for continuous casting comprising means forming a chamber having side and bottom walls containing a liquid coolant, a substantially horizontal mold at one end of said chamber having a casting bore with an outlet leading directly into said chamber below the upper edges of the sidewalls and into contact with the coolant at a substantial distance below the surface of the coolant in said-chamber,

means for continuously delivering molten material to be cast to said mold at a substantial pressure, means in said mold for cooling the peripheral walls of said casting bore and for precooling the material while in said bore into a partially solidified shaped state to form a casting in said bore with a molten core and a solid outer shell thick enough to cause the casting emerging from said bore to retain its cast shape in said coolant near said bore outlet, and means for advancing the casting as it is formed in said mold through said chamber substantially horizontally at a rate to cause the casting to emerge from said mold into said chamber in said partially solidified state, and to have at any one instant a substantial length of said casting in partially solidified condition immersed in said coolant, said distance being such that the pressure of the coolant acting on the periphery of said partially solidified casting is sufficiently high as said casting is so advanced through said chamber to counteract the core pressure in said casting and thereby to prevent rupturing of said solid shell due to said core pressure, said chamber being long enough and said rate being such as to cause said casting eventually to be sufficiently solidified while in contact with said coolant, to prevent outbreak of the molten core in the absence of coolant pressure.

2. A casting apparatus as described in claim 1, said chamber having an end wall, said casting bore being formed in said end wall, and said cooling means comprising passages in said end wall around said casting bore for circulating cooling fluid therethrough in heat exchange relationship with the material passing through said bore.

3. A casting apparatus as described in claim 1, comprising a wall for said chamber defining an outlet orifice horizontally aligned with said bore and having substantially the same crosssectional area and shape as the bore, whereby a casting formed in said bore may pass through said orifice after ad vancing through said chamber, and means for cooling the surfaces defining said orifice below the freezing point of the liquid coolant to form a thin layer of solidified coolant on the surface of the casting as it passes through said orifice. 

2. A casting apparatus as described in claim 1, said chamber having an end wall, said casting bore being formed in said end wall, and said cooling means comprising passages in said end wall around said casting bore for circulating cooling fluid therethrough in heat exchange relationship with the material passing through said bore.
 3. A casting apparatus as described in claim 1, comprising a wall for said chamber defining an outlet orifice horizontally aligned with said bore and having substantially the same cross-sectional area and shape as the bore, whereby a casting formed in said bore may pass through said orifice after advancing through said chamber, and means for cooling the surfaces defining said orifice below the freezing point of the liquid coolant to form a thin layer of solidified coolant on the surface of the casting as it passes through said orifice. 